Kate donned a glamorous Callas Evening Coat from Temperley London's Prefall 2014 Collection which she paired with simple black heels, while wearing her trademark bouncy brunette curls loose around her shoulders.
The Queen and Prince Phillip were also in attendance with several members of the royal family including Prince Charles and the Duchess of Cornwall, Prince Andrew, Prince Edward and his wife the Countess of Wessex.
Other royal family members who attended the event included Princess Anne and Vice Admiral Sir Tim Laurence, the Duke of Gloucester, the Duke and Duchess of Kent, Prince and Princess Michael of Kent and Princess Alexandra, the Honourable Lady Ogilvy.
The family were greeted by the President of the Royal Albert Hall, Mr Jon Moynihan and the President of the Royal British Legion, Vice-Admiral Peter Wilkinson. The members of the Royal family then took their seats in the royal box.
This year's festival marks the anniversaries of the centenaries of the Battle of the Somme and the Battle of Jutland, the 25th anniversary of the Gulf War and the 80th anniversary of the first flight of the Supermarine Spitfire.
Earlier in the day, Prince Harry attended the England vs South Africa rugby match in Twickenham, accompanied by Princess Charlene of Monaco. Before arriving at the match, the fifth-in-line to the throne visited the Rose and Poppy Gates to pay tribute to those who had lost their lives in WW1.